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111 lines
4.4 KiB
C++
111 lines
4.4 KiB
C++
/*
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* Copyright (c) 2012 The WebRTC project authors. All Rights Reserved.
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*
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* Use of this source code is governed by a BSD-style license
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* that can be found in the LICENSE file in the root of the source
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* tree. An additional intellectual property rights grant can be found
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* in the file PATENTS. All contributing project authors may
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* be found in the AUTHORS file in the root of the source tree.
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*/
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#ifndef WEBRTC_MODULES_AUDIO_CODING_NETEQ_MERGE_H_
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#define WEBRTC_MODULES_AUDIO_CODING_NETEQ_MERGE_H_
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#include <assert.h>
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#include "webrtc/base/constructormagic.h"
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#include "webrtc/modules/audio_coding/neteq/audio_multi_vector.h"
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#include "webrtc/typedefs.h"
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namespace webrtc {
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// Forward declarations.
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class Expand;
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class SyncBuffer;
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// This class handles the transition from expansion to normal operation.
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// When a packet is not available for decoding when needed, the expand operation
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// is called to generate extrapolation data. If the missing packet arrives,
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// i.e., it was just delayed, it can be decoded and appended directly to the
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// end of the expanded data (thanks to how the Expand class operates). However,
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// if a later packet arrives instead, the loss is a fact, and the new data must
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// be stitched together with the end of the expanded data. This stitching is
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// what the Merge class does.
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class Merge {
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public:
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Merge(int fs_hz, size_t num_channels, Expand* expand, SyncBuffer* sync_buffer)
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: fs_hz_(fs_hz),
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num_channels_(num_channels),
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fs_mult_(fs_hz_ / 8000),
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timestamps_per_call_(fs_hz_ / 100),
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expand_(expand),
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sync_buffer_(sync_buffer),
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expanded_(num_channels_) {
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assert(num_channels_ > 0);
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}
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virtual ~Merge() {}
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// The main method to produce the audio data. The decoded data is supplied in
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// |input|, having |input_length| samples in total for all channels
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// (interleaved). The result is written to |output|. The number of channels
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// allocated in |output| defines the number of channels that will be used when
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// de-interleaving |input|. The values in |external_mute_factor_array| (Q14)
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// will be used to scale the audio, and is updated in the process. The array
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// must have |num_channels_| elements.
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virtual int Process(int16_t* input, size_t input_length,
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int16_t* external_mute_factor_array,
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AudioMultiVector* output);
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virtual int RequiredFutureSamples();
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protected:
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const int fs_hz_;
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const size_t num_channels_;
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private:
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static const int kMaxSampleRate = 48000;
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static const int kExpandDownsampLength = 100;
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static const int kInputDownsampLength = 40;
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static const int kMaxCorrelationLength = 60;
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// Calls |expand_| to get more expansion data to merge with. The data is
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// written to |expanded_signal_|. Returns the length of the expanded data,
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// while |expand_period| will be the number of samples in one expansion period
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// (typically one pitch period). The value of |old_length| will be the number
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// of samples that were taken from the |sync_buffer_|.
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int GetExpandedSignal(int* old_length, int* expand_period);
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// Analyzes |input| and |expanded_signal| to find maximum values. Returns
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// a muting factor (Q14) to be used on the new data.
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int16_t SignalScaling(const int16_t* input, int input_length,
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const int16_t* expanded_signal,
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int16_t* expanded_max, int16_t* input_max) const;
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// Downsamples |input| (|input_length| samples) and |expanded_signal| to
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// 4 kHz sample rate. The downsampled signals are written to
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// |input_downsampled_| and |expanded_downsampled_|, respectively.
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void Downsample(const int16_t* input, int input_length,
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const int16_t* expanded_signal, int expanded_length);
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// Calculates cross-correlation between |input_downsampled_| and
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// |expanded_downsampled_|, and finds the correlation maximum. The maximizing
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// lag is returned.
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int16_t CorrelateAndPeakSearch(int16_t expanded_max, int16_t input_max,
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int start_position, int input_length,
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int expand_period) const;
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const int fs_mult_; // fs_hz_ / 8000.
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const int timestamps_per_call_;
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Expand* expand_;
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SyncBuffer* sync_buffer_;
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int16_t expanded_downsampled_[kExpandDownsampLength];
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int16_t input_downsampled_[kInputDownsampLength];
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AudioMultiVector expanded_;
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DISALLOW_COPY_AND_ASSIGN(Merge);
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};
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} // namespace webrtc
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#endif // WEBRTC_MODULES_AUDIO_CODING_NETEQ_MERGE_H_
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